If rental is un-necessary, or unwanted, you could go with a powered, two way Mackie
, on a tripod,...feed it with an good, inexpensive vocal mic. You'd need one XLR cable as long needed for the application,..likely 50', and if you want to double up the entire system with two powered speakers, the entire thing can be easily scaled up with a thru-put output on the first speaker to the second, which requires another 50' XLR.
You'll need a mic stand, found this
great bargain on a Shure SM58 mic, mic stand, and 20' cable. This isn't a typical weighted mic stand, however it'd be fine,...this appears to be quite a deal, as the SM58 (the world standard vocal mic) is typically $99 alone.
There are cheaper powered two ways, but none that I'm familiar with that I'd recommend. Go to your local pro audio dealer and discuss your needs, you'll be taken care of.